Shock-absorber.



R. M. LOVEJOY.

SHOCK ABSORBER.

APPLICATION FILED NOV. 10. I913. I LIM WI Patented Dec.14,1915.

Wii'nesses. 8 Inventor. I

. 55 59 60 Ralph MLovgjoyk W Atfy s.

RALPH IVI. LOVEIIOY, 01E MEREDITH, NEW HAMPSHIRE.

SHOCK-ABSORBER.

Specification of Letters Patent,

Patented n e. la, tale.

Application filed November 10, 1913. Serial No.- 800,02t.

To all whom it may concern:

Be it known that I, RALPH M. LOVEJOY, citizen of the United States,residing at Meredith, county of Belknap, State of New Hampshire, haveinvented an Improvement in Shock-Absorbers, of which the followingdescription, in connection with the accompanying drawing, is aspecification, like characters on the drawing representing like parts.

This invention relates to improvements in shock absorbers and especiallythat type which is adapted for use upon automobiles and other vehiclesWhich are subject to heavy jolts. In order that the body of the vehiclemay be free from substantial vibration which will annoy the passengersit is desirable that comparatively light springs beused which will yieldto light shocks and that said springs be supplemented by a cushioning orshock absorbing means which is adapted to dissipate the effect of themore severe shocks due to striking large obstruEtions in the road orpassing over deep gullies.

The present invention therefore .comprises a hydraulic shock absorberwhich is adapted to be so arranged as to be practically inoperativeduring slight shocks, but which will destroy or lessen the effect of themore severe shocks. I am aware that heretofore shock absorbers of thisgeneral type have been madein which the fluid used is usually oil, butin such devices there is a great deal of leakage of the oil around thestuffing box which surrounds the piston of the hydraulic cylinders. Thisleakage eventually causes such diminution of the amount of oil containedin the cylinder as to interfere with the effectiveness of the shockabsorber. The exuded oil collects dirt and thereby hastens the wearingaway of movable parts and also by running down the exterior of thedevice gives it an unsightly appearance.

One of the objects of the invention is to provide a hydraulic shockabsorber in which there is no necessity for a stuffing box for thepiston rod, and in the present invention means have been devised wherebyany oil which may leak out around the piston rod through its journal inthe cylinder head will be speedily and completely returned to thecylinder.

Another object of the invention is to provide means whereby the rate offlow of the fiuid through the piston head may be regulated in such amanner that the shock absoiiber will be responsive to severe shocks ony.

Another object of the invention is to provide a valve of such acharacter as to per-- axle and body of a vehicle of such a char 7o acterthat rattling will be avoided.

Other objects of the invention will more fully appear from thedescription and annexed drawing, and the following claims.

The drawing represents a vertical axial section of one of the preferredforms of apparatus in which this invention is embodied.

The shock absorber illustrated in the accompanying drawing comprises acylinder having a body 1 and an end 2 preferably cast integral therewithand having thickened portion or ring 3 adjacent the opposite end of saidbody. The cylinder is provided with a piston which preferably comprisesa chambered head 4 and a rod 5 castintegrally with the piston head I.The piston rod extends through a loosely mounted and movable cylinderhead 6 as will hereinafter be explained.

The end 2 of the cylinder is provided with a projection 7 which isapertured to receive a supporting member 8 attached to or extending fromthe axle of the vehicle. The piston rod 5 is preferably screw threadedat its end into a circular casting 9 having a boss 10 adapted to receivea member 11 projecting from or secured to the body of the vehicle.

In hydraulic shock absorbers considerable difficulty is experiencedbecause of the tendency of the oil to leak out along the piston rodthrough its bearing in the cylinder head, thus lessening the supply ofoil in the cylinder and eventually rendering the device inefiective.shock absorbers in operative condition it has heretofore been necessaryto provide a In order to maintain the stufling box. in the cylinder headfor the piston and to keep a packing screwed tightly around the pistonbut inasmuch as the shock absorbers are usually placed beneath the bodyof the vehicle in position which is diflicult of access they are likelyto be neglected and in the course of a short time suflicient oil willleak out to render the device useless.

In the present invention the necessity for a stufling box or otherpacking gland is eliminated, and provision is made for returningwhatever oil by chance oozes out around the piston rod directly to thecylinder, thereby avoiding a loss of fluid which would render the deviceineffective or inoperative. This is accomplished in the embodiment ofthe invention disclosed herein by providing a chambered cap 15 for.theend of the cylinder, which is preferably attached thereto by a screwthreaded connec tion extending from the end of the cylinder to the edgeof the thickened portion of the cylinder body 3, the cap being ofsubstantially the same external diameter as the outer diameter of saidthickened portion or ring. This cap forms an auxiliary chamber adaptedto receive any oil or other fluid which may ooze out from the bearingaround the piston rod.

In order to provide means whereby the oil thus escaping mayreturn'directly to the cylinder, the cylinder head 6 is independentlysupported between the end of the cylinder body and an annular ledge 16projecting inwardly from the ca 15. The ledge 16 is spaced from the endof the cylinder a distance slightly greater than the thickness of theedge portion 17 of the cylinder head so that the latter is capable of aslight movement in unison with the piston during its reciprocation. Theedge of the cylinder head 6 is preferably provided with an annulargroove 18 which communicates with openings or apertures 19 leading intothe cylinder. The cylinder head 6 may also be provided with an oilpacking groove 20 to check the flow of any escaping oil, and an opening21 leading from said groove being preferably provided to permit the oilin the groove to escape into the cap chamber whence it returns to thecylinder proper.

In the operation of the device a severe jolt will just cause the pistonto descend against the resistance of the fluid in the lower part of thecylinder, which is permitted to escape through restricted openings inthe piston head as will hereinafter be explained, until the shock hasbeen dissipated. Upon the rebound or return movement the piston ascendsand the movable cylinder head 6 is carried upwardly by the piston rod 5until the upper surface of the outer portion 17 seats upon the inwardlyproject- .5 ing ledge 16 of the cap. The contacting surfaces of thecylinder head and the ledge 16 are so ground as to provide a tight jointwhich will prevent the fluid from the cylinder passing into the capchamber. The return shock is absorbed during the-further movement of thepiston by the resistance of the fluid passing downwardly through thepiston head in a manner hereinafter to be described. After the shock hasbeen absorbed the piston head will descend to its normal position, andupon its descent the cylinder head 6 will move in unison with it untilit seats upon the end of the cylinder body. By this movement thecylinder head will be removed from its contact with the internal ledge16 of the cap thus providing an opening through which any oil which mayhave found its way into the cap chamber may run down into the groove 18of the cylinder head, and thence through the apertures 19 into thecylinder proper. This return of the oil through the cylinder is causednot only by the action of the force of gravity, but in addition theretoby such vacuum as has been created in the cylinder by the upwardmovement of the piston, so that the oil or fluid in the chamber isforcibly drawn back into the cylinder body.

As before stated it is desirable that the shock absorber remainsubstantially unresponsive to the effect of light shocks and toaccomplish this result the inner surface of the cylinder body isprovided in its middle portion with a series of grooves which areadapted to permit the free passage of the fluid from one side of thepiston to the other during a short reciprocation of the piston. Thesegrooves, may, if desired, be made in graduated lengths increasing fromthe middle of the cylinder so that as the piston moves from its normalposition the resistance to such movement will be gradually increased.

In order to make the piston effective against heavy shocks only, a valveis provided in the piston head which is retained in place by a spring ofa determined resistance so that the piston head remains substantiallyclosed against the passage of fluid through it, except when sufficientstress is presented to overcome the resistance of the spring.

In the preferred form of the invention illustrated herein, the pistonhead 4. is in the form of a short cylinder, the upper portion 25 of saidpiston head, its edges and the piston rod 5 being preferably castintegral. The upper portion 25 of the piston head is provided withapertures 26 of sufficient size to allow the fluid in the cylinder topass freely from one side of the piston to the other. The other end ofthe cylindrical piston head 4 is provided with an internal disk 27 whichis preferably screwed into the edge of the piston head and provided withaperiaieaevi In order to restrict and regulate the flow of the fluidfrom the piston head a valve 29 is placed within the chamber in thepiston head.- This valve is preferably bell-shaped in fprm and is seatedupon the disk 27 outside of the apertures 28. It is provided with a"stem 30 which extends upwardly into a cylindrical recess in the pistonrod, a spring 31 being interposed between the end 32 of the cylindricalrecess in the piston rod and the upper end of the valve stem 30. Byproviding a strong spring to maintain this valve seated the shockabsorber will respond only to such shocks as will overcome the resistance of the spring 31. Upon such shocks the bell-shaped valve 29will be raised from its seat and the fluid allowed to escape from thelower to the upper part of the cylinder through the ports 26 and 28 inthe piston heads as the piston descends. By reason of the large area ofthe valve 29 the initial flow of oil through the cylinder head upon asevere shock will be. relatively great permitting the piston at first todescend rapidly, but as the energy of the shock becomes ab sorbed by theresistance of the fluid passing through the ports in the piston head,the spring will gradually force the valve 29 toward its seat thusincreasing the resistance to the passage of the fluid through the pistonhead until the valve is seated and the piston head gradually comes torest.

The spring 31-may, of course, be made of such strength as may be desiredto give the proper degree of sensitiveness to the shock absorberaccording to the conditions under which it is to be used.

The valve 29 is preferably provided with a small port 33 through whichthe fluid may flow during a slow movement of the piston.

It is desirable that the piston head return readily to its normalposition after having performed its function of absorbing a shock and inorder to effect this result the bellshaped valve 29 is provided with aseries of ports 35 which are adapted to be closed by a valve locatedwithin said bell-shaped valve. This valve as illustrated in the drawingherein comprises a disk 36 adapted to seat upon the under surface of ahorizontal portion 37 of the bell-shaped valve. The disk valve isprovided with a. hollow stem which is adapted to fit and extend upwardlyinto the stem 30 of the bell-shaped valve. The disk 27 is preferablyprovided with a stud which projects upwardly and fits within the hollowstem 38 of the valve 36. A spring 41 is interposed between the upper endof the stud 40 and the under part of the end of the stem 38. The springserves to retain the valve 36 normally against the seat 37.

It will be obvious that in operation the downward movement of the pistonwill tend to hold the valve against its seat 37 Upon the backward orupward movement of the piston, however, the valve 36 will be-withdrawnfrom its seat by the pressure of the fluid against its upper surface,and inasmuch as the spring 41 is relatively weak the fluid will readilyflow from the upper portion of the cylinder to the lower, through theports 26 in the upper portion 25 of the cylinder head, the ports 35 inthe bellshaped valve and the ports 28 in the lower portion or disk ofthe piston head.

Inasmuch as shock absorbers ofnecessity must be subject to considerablestrain and often receive unexpected and very heavy shocks it isnecessary that some means be provided whereby an excessive shock willnot break the cylinder. Tn the present case provision is made againstsuch accident by leaving a short air space at the top of the cylinderadjacent to the upper cylinder head, and in order that the user will beprevented from filling the shock absorber too full of fluid the aperturethrough which the fluid may be introduced into the cylinder is placed ashort distance below the upper end of the cylinder body.

In the apparatus illustrated herein a hole is bored through thethickened portion 3 of the cylinder body and the outer portion of saidaperture enlarged to form a screw threaded seat 51 into which a plug 52may be screwed to close said aperture. The plug 52 is preferablyprovided with a square recess 53 adapted to receive a suitable tool toremove and replace said plug.

In order that the shock absorber may be noiseless I have devised meanswhich will retain its connection to the relatively vibrating members,such as the axle of the automobile and the body of the vehicle, inconstant engagement. In the embodiment of the invention shown herein thestud or projection 7 from the cylinder head 2 and the extension 10 fromcircular support 9 for the end of the piston rod are apertured and theapertures are provided with tapered steel bushings 55. The members 8 and11 which are attached respectively to the axle and carriage body areturned down and shouldered as at 56 to form stems 57 for the receptionof suitable metallic wearing rings 58 having spherical surfaces engagingthe bushings. These wearing rings 58 are preferably of a softer materialthan the steel bushings aforesaid, so that the rings will wear withoutinjury to the bushings. In order to advance the wearing rings into thetapered bushings as said rings wear, the studs 57 are Preferablyprovided with helical springs 59 which bear rigidly at one end againstthe face of the apertured projections and are provided at the other endswith pairs of set nuts 60, 61 through which any and embraces the upperend of the cylinder cap 15 and which prevents the access of dust to thepiston rod 5.

In order to further protect the piston rod against fine dust I haveprovided the upper portion of the cap 15 with an annular projection 63which is screw-threaded upon its outer side and provided with a cap 64adapted to inclose a small amount of felt or other packing 65. It is tobe understood that the function of this felt packing is merely toprevent dust from adhering to the piston stem and thereby being drawninto the cap chamber, but that it does not serve as the stufiing box inany sense.

It is to be understood that the construction disclosed herein is one ofthe preferred forms of my invention but that it may be embodied invarious other forms and that the disclosure herein is illustrative andnot restrictive.

Having thus described my invention, what I claim as new and desire tosecure by Letters Patent is:

1. A shock absorber comprising a hydraulic cylinder containing aquantity of liquid, a reciprocable piston submerged in said liquid andhaving a piston rod extending through a bearing in the cylinder head iand means actuated by the piston in its stroke in one direction forpermitting the return of any liquid which has leaked through the bearingfor the piston rod during the motion of the piston in the oppositedirection, whereby the necessity of a stufiing box for the cylinder iseliminated.

2. A- shock absorber comprising a hydraulic cylinder containing aquantity of liquid, a movable head therefor, a piston submerged in theliquid in said cylinder and having a piston rod extending through abearing in said cylinder head, a supplementary chamber inclosing saidpiston head and means carried by said head adapted to prevent oil frompassing from the cylinder during the movement of the piston in onedirection and to permit the return of fluid to the cylinder during themovement of the piston in the opposite direction whereby any leakagealong the piston rod is returned to the cylinder and the necessity of astufling box avoided.

3. A shock absorber having a hydraulic cylinder, and piston and ayieldable cylinder head through which the iston rod extends,

a seat for said head a apted to prevent the passage of fluid from saidcylinderwhen the piston rod is moved in one direction, and meansoperated upon the opposite stroke of the piston to cause the return tothe c linder of any fluid which may have leake out during thefirst-mentioned movement.

4. A shock absorber comprising a hydraulic cylinder and piston, acylinder head adapted to move slightly in unison with the piston, seatsfor said cylinder head adapted to prevent the passage of fluid from thecylinder when the piston is moved in one direction and to permit thereturn of leakage to the cylinder upon movement of the piston in the oposite direction.

5. A shock a sorber comprising a hydraulic cylinder and piston, asupplementary chamber inclosing the cylinder head through which thepiston rod extends, a ledge projecting inwardly from the wall of saidsupplementary chamber to form a seat for the upper surface of saidcylinder head, and to limit the movement thereof relative to the end ofthe cylinder, recesses in the periphery of the cylinder head adapted tocommunicate with the cylinder through the under surface of said cylinderhead, whereby the passage of fluid from the cylinder is prevented whenthe piston is moved upwardly and the return to the cylinder of leakagepermittcd when the piston is moved downwardly to normal position.

6. In a shock absorber comprising a hydraulic cylinder, a reciprocablepiston provided with apertures to permit the flow of fluid from one sideof said piston to the other, a spring actuated valve adapted to restrainthe flow of fluid in one direction and a supplemental spring actuatedvalve wholly inclosed within said first-mentioned valve adapted tocontrol the flow of fluid through said piston in the opposite direction.

7. In a shockabsorber comprising a hydraulic cylinder, a piston providedwith apertures to permit the flow of fluid from one side of said pistonto the other, a valve adapted to substantially close said aperturesagainst the upward passage of fluid provided with a relatively stifl'spring whereby the cushioning effect of the device will be operativeonly under heavy shocks and an oppositely disposed valve provided with arelatively light spring adapted to permit the fluid to flow readilythrough said piston upon its return to normal position.

8. In a shock absorber comprising a hydraulic cylinder a piston having acylindrical chambered head and a rod havingarecess communicating withthe chamber in said head, apertures through the ends of the piston head,a Valve inclosed in said chamber and seated on one of said ends having astem in said chamber and seated on one of said ends and having a stemextending into the recess in the cylinder rod, a spring sup ported insaid recess adapted to normally seat said valve and to limit the same tomovement upon relatively severe shocks, and

a reversely operating valve normallyclosing the aperture infirst-mentioned valve but adapted to open to permit the piston to returnto normal position.

10. In a shock absorber comprising a hydraulic cylinder, a piston havinga chambered head and a rod having a recess communicating with thechamber in said head, apertures in the ends of the piston head, a valveprovided with an aperture interposed in said chamber and seated on oneof said ends and having a stem extending into the recess in the cylinderrod, a spring supported in'said recess adapted to. normally seat saidvalve and to limit the same to movement upon relatively severe shocks,and a reversely operating spring-actuated valve normally closing theaperture in first-mentioned valve but adapted to open to permit thepiston to return to normal position.

11. In a shock absorber comprising a hydraulic cylinder, a piston havinga chamltu bered head and a rod having a recess communicating with thechamber in said head, apertures in the ends of the piston head, a

valve provided with an aperture inter osed in said chamber and seated onone 0' said ends and having a stem extending into the recess in thecylinder rod, a spring supported in said recess adapted to normally seatsaid valve and to limit the same to movement upon relatively severeshocks, a reversely operating valve having a hollow stem, a studprojecting from the lower piston head into said hollow stem, a springinterposed between the end of said stud and the end of the recess insaid valve adapted to normally seat the inner valve upon the undersurface of said first-mentioned valve but adapted to yield to permit thepiston to return'to normal position.

12. lln a shock absorber comprising a hy draulic cylinder, an aperturedpiston and means for regulating the passage of fluid through saidpiston, a piston rod, a support ing member connected to the outer end ofsaid piston rod, a dust guard secured to said supporting member anddepending therefrom to inclose said piston rod and-cylinder .to protectthe relatively moving parts and to prevent dust from obtaining access tothe fluid chamber and means operable by the reciprocation of the pistonto cause any oil which leaks-through the piston rod bearing to bereturned to the cylinder.

lln testimony whereof, I have signed in name to this specification, inthe presence of two subscribing witnesses.

RALPH M. LOVEJOY.

Witnesses:

FREDERICK A. llnNivA v'r, THOMAS J. DRUMMonp.

